Fuel-air mixture control

ABSTRACT

An improved fuel-air mixture control for connection between the control unit and a temperature sensor of a fuel injection system of a vehicle. The fuel-air mixture control is located adjacent the area occupied by the vehicle operator and has a selector switch which selectively disconnects the temperature sensor from the control unit and connects the control unit to a variable resistor.

United States Patent Maier June 10, 1975 FUEL-AIR MIXTURE CONTROLPrimary Examiner-Charles J. Myhre Assistant Examiner-Ronald B. Cox [76]lnvsmor' gl g' 22 253? Runnels Fort Attorney, Agent or Firm-Richards.Harris &

Medlock [22] Filed: July 16, I973 [21] Appl. No.: 379,611 [57] ABSTRACTAn improved fuel-air mixture control for connection 5 CL. 123/32 123/193123/193 3 between the control unit and a temperature sensor of 51 Int.Cl. F02h 3/00 a fuel injection System of a vehicle The fuel-air [58]Field of Search 123/32 EA We comm is located adjacent ma Occupied by thevehicle operator and has a selector switch which [56] References cselectively disconnects the temperature sensor from UNITED STATESPATENTS the control unit and connects the control unit to a variableresistor.

3,05l,l52 8/1962 Paule ct al l23/32 EA 1 Claim, 2 Drawing FiguresPATENTEDJUH 10 m5 CONTROL UNIT FIG. 7

l ?6 5a 44 37 68 72 bill 58 6 W 704 qso] *1 /L Ji J 59 CONTROL UNIT FIG.2

FUEL-AIR MIXTURE CONTROL BACKGROUND OF THE INVENTION The presentinvention relates generally to improvements in fuel injection systems.In another aspect, this invention relates to a new and improved fuel-airmixture control for a fuel injection system which can control the fuelused by the engine to improve efficiency and performance.

DESCRIPTION OF THE PRIOR ART Internal combustion engines with fuelinjection systems have been used on vehicles for a number of years. Onesuch system in present use was designed by Robert Bosch for use on theVolkswagen automobile.

The Bosch electronic injection system is of the type which uses alow-pressure. intermittently operating time injection system with fuelinjected by electromagnctically actuated injectors. The injectors are ofa constant lift type, and since the fuel is injected under constantpressure, the injected quantity is a function of time only.

The required amount of fuel injected is determined according toparameters of the engine such as speed, load (manifold pressure) andtemperature. Transducers are provided on the engine which measure theseparameters. These transducers are connected to an electronic controlunit which contains electronic circuitry which controls the quantity offuel injected in response to the output of these trnasducers. Thus, thebasic fuel quantity requirement is determined by a combination of thefactors of engine speed, engine load and temper ature.

For example, when an engine is started cold, extra fuel is required andthis information is supplied by a temperature transducer mounted in thehead of the engine. As the temperature of the engine increases, theamount of fuel necessary for operation of the engine is decreased.

One problem which has been present in the operation of these fuelinjection systems is the provision ofa convenient means by which theamount of fuel injected on each cycle can be conveniently adjusted bythe vehicle operator during periods of prolonged operation at constantspeeds and torques. An example is highway driving when the engine isoperated at a high speed and a low torque. During the highway driving,it is sometimes desirable to adjust the fuel-air mixture to maximizepower or fuel use efficiency of the engine. In addition, in someinstances, a failure or misadjustment of the various components of thesystem make it desirable to manually control the fuel-air mixture of theengine.

Therefore, according to the present invention, an improved fucl-airmixture control is provided in the vehicle adjacent to the operatorwhich includes a switching means for interrupting the connection betweenthe temperature transducer of the engine and its respective control unitand substituting a variable resistance means which can be adjusted bythe operator of the vehicle during use of the vehicle.

OBJECTS OF THE INVENTION An object of the present invention is theprovision of an improved fuelair mixture control system for a fuelinjection system.

Another object of the present invention is the provision of an improvedfuel-air mixture control which allows manual adjustment of the fuelmixture of the fuel injection system during operation of the vehicle.

A further object of the present invention is the provision of animproved fuel-air mixture control which is simple and inexpensive tomanufacture, install and operate.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated by those of ordinary skill in the art as thesame becomes better understood by reference to the following DetailedDescription when considered in connection with the accompanying Drawingsin which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I illustrates a schematic diagramof a conventional fuel injection system of a vehicle; and

FIG. 2 is a schematic diagram ofa portion of the fuel injection systemillustrated in FIG. 1 with the improved fuel-air mixture control of thepresent invention installed.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the Drawings,wherein like reference characters designate like or corresponding partsthroughout the several views, there is illustrated in FIG. I a schematicdiagram of the low-pressure Bosch fuel injection system which is used onvarious Volkswagen and Porsche automobiles. An example is found on thePorsche 9144 which is powered by the Volkswagen 4]] engine and theAugust I967 through I973 Vollc swagens with type three engines.

This fuel injection system 10 comprises a fuel tank I2 with a fuelsupply line 14, a fuel filter l6 and a fuel pump 18 connected thereto.Pump 18 supplies pressurized fuel through a fuel line 20 to a fuelmanifold system 22. This system 22 is in turn connected by means of fuelline 24 to a pressure regulator valve 26 which maintains manifold 22 ata constant pressure. When the pressure in the manifold 22 exceeds thedesired minimum (approximately two atmospheres) fuel is returned to tankI2 from the manifold 22 through valve 26 and return line 28.

Fuel manifold 22 has a plurality of fuel ports 30 which correspond innumber to the number of cylinders in the particular engine. In thepresent case, four ports 30 are provided with each port connected bymeans of a conduit to a separate fuel injector 32. In FIG. I only onefuel injector 32 is illustrated, but it is to be understood, of course,that the other cylinders each have an identical fuel supplyconfiguration.

Each injector 32 comprises a valve which is electrically controlledthrough a line 33 from control unit 35 as will be hereinafter describedin more detail, to inject a quantity of fuel into the intake port 34behind the intake valve 36. An example of this control unit iscommercially available on the I970 Volkswagen type III and has partnumber 3 II 906 OZID.

The fuel injected into port 34 is mixed with a quantity of air flowingthrough the intake air distributor line 38. A pressure transducer iselectrically connected to control unit 35 through conductor 42 tomeasure the parameter of engine load. Through this connection, controlunit 35 can monitor the pressure in line 38.

In addition, a variable resistance temperature sensor 44 is providedattached to the head 37 of the vehicle engine. This temperaturetransducer or sensor 44 is of the resistance type and varies inresistance in response to the temperature of the head. Sensor 44 isconnected by means of a conductor 46 to control unit 35 so that controlunit 35 can monitor the temperature of head 37. This sensor iscommercially available from the Volkswagen Company as part number 31 l906 l6lC.

The distributor 48 of the engine is also connected by means of conductor50 to control unit 35 so that the control unit can monitor the speed ofthe engine.

In operation, as the temperature of the head 37 varies, transducer 44varies in resistance. Appropriate circuitry is provided in the controlunit so that the change in resistance will be sensed and injector 32will be caused to inject more fuel into intake port 34. Likewise, as theengine becomes hotter, control unit 35 will cause injector 32 to injectless fuel into the intake port on each cycle. In addition, the pressureof the inlet air and the speed of rotation as monitored will effect theamount of fuel injected during each cycle.

Turning now to FIG. 2, the improved fuel air-mixture control of thepresent invention is illustrated. In this figure, temperature transducer44 is illustrated grounded at its case with its conductor 46disconnected from conductor 46 and control unit 35 and attached toconductor 52. This conductor 52 is connected to the mixture controlcircuit 54 of the present invention. This circuit 54 is positioned inthe automobile adjacent to the operator so that the circuit can beadjusted during operation of the vehicle. The conductor 52 is connectedto one contact 56 of a single pole triple throw switch 58. The switchhas a control arm 59 which operates a switch arm or wiper 60 which isconnected to control unit 35 by means of the conductor 46. Thus bymoving wiper 60 so that it makes contact with contact 56, thetemperature transducer 44 can be connected to control unit 35 in theconventional manner.

A second contact 64 is provided on the switch 58 and is connected to a kohms variable resistor 66. The contact 64 is connected to the wiper 68of resistor 66 while one end of the resistor 66 is grounded at 70. Acontrol arm 71 is provided for adjusting the resistor 66. By operatingthe switch 58 to connect the wiper 60 to contact 64, control unit 35 canbe connected to resistor 66. The resistor 66 can then be manuallyadjusted by arm 71 to vary the fuel-air mixture as desired duringoperation of the engine.

A third contact 72 is provided on the switch 58 and this contact is leftblank. By moving the switch 58 to a position such that wiper 60 isconnected to contact 72,

control unit 35 is disconnected from either the resistor 66 or thetemperature transducer 44, and in this position, the engine will notstart.

During normal operation of the engine, the switch 58 is left in positionwherein the wiper is connected to contact 56 and control unit 35 isconnected to the temperature sensor 44. During long highway trips, andthe like where it is desired to economize on fuel or increase power, theswitch 58 can be moved until wiper 60 is connected to contact 64 withresistor 66 connected to control unit 35. The control arm 71 of thepotentiometer 66 can then be adjusted to achieve the maximum power byholding the accelerator in a given position. In this manner, the fueleconomy can be improved by leaning out the engine.

It is to be understood, of course, that the foregoing relates to onlythe preferred embodiment of the present invention and numerousalterations may be utilized to practice the present invention withoutdeparting from the spirit and scope as defined in the appended claims.

I claim:

1. In combination with a fuel injection system for a vehicle engine ofthe type wherein a temperature responsive variable resistance transduceris placed in contact with the engine, the transducer varies inresistance and is connected to a fuel control means to vary the amountof fuel injected into the engine in response to the temperature of theengine, the improvement which comprises:

a. a variable resistor means adjustable within the operating range ofsaid transducer;

b. triple throw switch means which when engaged can selectively:

I. connect said variable resistor means to said control means wherebythe operator of the vehicle may manipulate the variable resistor meansto control the amount of fuel injected into the engine,

2. connect said transducer to said control means,

and

3. disconnect said control means and said variable resistor means fromsaid transducer whereby starting of the engine is prevented; and

c. said variable resistor means and said switch means are positioned onsaid vehicle so that the operator thereof can manipulate said variableresistor means and said switch means while operating said vehicle.

1. In combination with a fuel injection system for a vehicle engine ofthe type wherein a temperature responsive variable resistance transduceris placed in contact with the engine, the transducer varies inresistance and is connected to a fuel control means to vary the amountof fuel injected into the engine in response to the temperature of theengine, the improvement which comprises: a. a variable resistor meansadjustable within the operating range of said transducer; b. triplethrow switch means which when engaged can selectively:
 1. connect saidvariable resistor means to said control means whereby the operator ofthe vehicle may manipulate the variable resistor means to control theamount of fuel injected into the engine,
 2. connect said transducer tosaid control means, and
 3. disconnect said control means and saidvariable resistor means from said transducer whereby starting of theengine is prevented; and c. said variable resistor means and said switchmeans are positioned on said vehicle so that the operator thereof canmaniPulate said variable resistor means and said switch means whileoperating said vehicle.
 2. connect said transducer to said controlmeans, and
 3. disconnect said control means and said variable resistormeans from said transducer whereby starting of the engine is prevented;and c. said variable resistor means and said switch means are positionedon said vehicle so that the operator thereof can maniPulate saidvariable resistor means and said switch means while operating saidvehicle.